(1) Field of the Invention
The present invention relates to a multimode wireless communication apparatus conformed with a plurality of communication standards and a high frequency integrated circuit therefor.
(2) Description of the Related Art
Communication modes (communication protocols) in wireless terminals are broadly divided into a wireless communication protocol for mobile telephone network such as GSM, EDGE, GPRS, PDC, cdmaOne, cdma2000, and W-CDMA each using a public network of a wide area (hereinafter, called public network wireless communication protocol), and a communication protocol for wireless LAN such as IEEE802.11a, 11b, 11g, and 11h and HiperLAN/2 using a local network. The wireless communication protocol using a local network also includes, for example, a short-range wireless communication protocol such as by Bluetooth or UWB.
In the specification, the local network wireless communication protocol includes the above short-range wireless communication protocol. A wireless terminal (wireless communication apparatus) having two communication modes, one for the public network wireless communication protocol and the other for local network wireless communication protocol will be called a multimode wireless terminal.
In the field of wireless communication, recently, a mobile telephone network having a wide service area is rapidly spreading. Meanwhile, in the metropolitan area, information service using a local high-speed network such as a wireless LAN has also started. Thus, various wireless communication systems coexist today. A mobile telephone terminal has advantages such that a communication area is wide and communication can be continued even when the user is moving among cells at high speed. However, the bit rate is as low as 9.6 to 384 kbits/second and the communication cost is expensive. On the other hand, at present, information service areas of a wireless LANs are limited to, for example, service areas called hot spots in the metropolitan area. Unlike mobile telephone systems, the wireless LAN cannot provide communication service to the user who is moving at high speed. However, as compared to a mobile telephone, the wireless LAN can provide a higher bit rate service (for example, 22 to 54 Mbps), its communication cost is overwhelmingly cheaper, and there exist a number of service areas which are free of communication charges.
Consequently, the demand for a multimode terminal adapted to a plurality of communication standards, so that both of the services can be received by a single wireless terminal is increasing. A multimode wireless terminal conventionally proposed has plural kinds of transceivers adapted to different communication protocols (communication modes), so that the user can selectively use one of communication modes or use two modes in parallel independently of each other.